Transformer



i v s 7/ MMW M M m 'Jan. 29, 1929 TRANSFORMER Filed Aug. 12, 1927 Patented Jan. 29, 1929.

PATENT OFFICE.

FRANK M. SPARKS, OF CULLMAN, ALABAMA.

TRANSFORMER.

Application filed August 12, 1927. Serial No. 212,544.

This invention relates to the obtaining of fractional turn ratios of transformers by a method particularly applicable to current transformers of present design.

Current transformers, particularly those for use, with instruments, are provided with a small number of turns in the primary and secondary windings. Since any turn which passes thru the core window counts as a full turn and any turn which does not pass thru the core window does not count at all, it is not usually possibleto obtain a fractional turn. This is a disadvantage in transformers of the type mentioned as the addition or subtraction of a complete turn from the primary or secondary may give ratios which are distant several per cent from the ratios desired.

A fractional turn ratio has previously been obtained by using two parallel secondary windings, the two windings having an unequal number of turns.

It is an object of my invention to obtain a fractional turn with the use of but one secondary Winding.

The foregoing and other objects are attained in the embodiment of the invention shown in the drawing, in which The figure shows in diagrammatic perspccfive a transformer constructed according to my invention.

In its preferred form my invention comprises a transformer core having a passage in one of the legs thereof thru which a convolution of the winding can be passed.

As shown in the figure, I preferably provide a transformer core 6 having a' leg 7 around which a primary coil 8 is mounted. The primary coil can be equipped with suitable terminals 9 and 10 connecting with leads 12 and 13 to a source of electricity. Also mounted on the core 6 and preferably encompassing the leg 7 is a secondary winding 14. This winding leads from a terminal 16 around the leg 7 a whole number of turns, in each case passing thru the core window 17.

To obtain a fractional turn in accordance with my invention, 1 lead the secondary wind ing let thru a passage 18 piercing the leg 7 and anchor it to a terminal 19. The character and disposition of the passage 18 is subject to considerablewariation dependent upon the conditions to be fulfilled, but in any event produces the desired turn ratio effectively and without complication.

It is to be understood that I do not limit myself to the form of transformer shown and described herein, as the invention, as set forth in the following claims may be embodied in a plurality of forms.

I claim:

1. A transformer comprising a core having an aperture formed therein, and a winding on said core, said winding having a portion thereof completely surrounding the core and another portion thereof passing through the aperture in the core.

2. A transformer comprising a core having an aperture formed therein, and a winding on the core, said winding having a plurality of turns completely surrounding the core and at least one turn passing through the aperture in the core.

3. A transformer comprising a closed core having an aperture provided through one leg of the core, a winding on the core, one portion, of said winding encompassing the core and another portion of said winding encompassing only a portion of the core to provide fractional turn ratios.

1. The method of winding a transformer core to obtain fractional ratios which comprises providing the core with an aperture through the body thereof and placing a part of the winding around the body of the core and placing another part of the winding through the aperture provided in the core.

FRANK M. SPARKS. 

